1. Field of the Invention
The present invention relates to optical tweezers which trap one or more objects existing in the convergence position and the vicinity thereof, by forming an optical trap in an output beam convergence position.
2. Related Background Art
In known optical tweezers, a beam is converged in a predetermined position, and a minute object existing in a sample solution or the like, such as a cell, a chromosome, or a nanomachine, is trapped with no contact and no breakage using the optical force of the converged beam. The optical tweezers form an optical trap capable of trapping the minute object with the optical force of the converged beam in the convergence position of the beam and the vicinity thereof, and is capable of moving the object trapped in the optical trap to an arbitrary position within the sample solution by scanning the convergence position of an emitted laser beam, for example.
Japanese Unexamined Patent Application Publication 2004-138906 (Document 1) discloses optical tweezers in which a beam is converged in each of plural trapping positions so that an optical trap is formed in each trapping position using the optical force of the converged beam, and an object is trapped in each of the trapping positions. In these optical tweezers, the trapping positions are controlled by dividing a modulation surface of a spatial light modulator into plural regions corresponding to the respective trapping positions such that a phase pattern is formed independently in each divided region. In so doing, the plural objects trapped respectively in the plural trapping positions can be moved individually. When moving one of the trapped objects, only the phase pattern of the region corresponding to the object need be updated, and hence the objects can be moved rapidly.
In “3D manipulation of particles into crystal structures using holographic optical tweezers”, Jonathan Leach et al., OPTICS EXPRESS, 2004 OSA (Optical Society of America), Jan. 12, 2004, pp. 220-226 (Document 2), a method of moving plural objects simultaneously and three-dimensionally using optical tweezers is described. However, Document 2 does not disclose the formation of independent phase patterns in each region of a modulation surface.